Working with four-point tracking

Four-point tracking in After Effects, also known as corner-pin tracking, involves tracking the motion of four specific points in a video frame. This technique is used when you need to replace or modify the contents of a rectangular area, such as a TV screen, billboard, or the side of a building.

We will be using four-point tracking to replace the laptop screen in the 4 Point Tracking composition in the Laptop.mp4 layer with the War Scene.mp4 layer, which we created in Chapter 10 while working with particle simulation.

Before we jump into tracking, we will have to increase the duration of the War Scene.mp4 footage from 5 seconds to 10 seconds, for which we will be using the Time Stretch option in After Effects, so that it matches the duration of the Laptop.m4 footage.

Time Stretch

Firstly, we need to extend the timing of the War Scene.mp4 layer in the 4 Point Tracking composition because the duration of the War Scene.mp4 layer is only 5 seconds...